The present invention relates to an improved mechanical disc brake in which when the brake is released, the lining assemblies for tightly clamping the brake disc are restored to their home positions and kept spaced from the brake disc by an optimal gap.
In a conventional bicycle-used disc brake, lining assemblies are mounted on opposite inner faces of an inner and an outer sections of a caliper. When braking, a steel cord is pulled to drive a brake lever so as to make the lining assemblies tightly clamp the brake disc. When the brake is released, the brake lever is restored to its home position. At this time, the brake disc is released from the clamping force of the lining assemblies. Accordingly, a rider can decelerate or stop the bicycle. Some shortcomings exist in the above arrangement as follows:
1. In the conventional brake, via an adjustment piston and a thread rod, the lining assemblies are synchronously forward pushed by the brake lever so as to achieve a braking effect. These components are not interconnected so that when releasing the brake, only the brake lever is restored to its home position due to releasing of the pull cord, while the other components such as adjustment piston and lining assemblies will still intermittently or continuously contact with the brake disc depending on the road condition. Therefore, during running, a frictional force is created to waste the strength of the rider.
2. In the conventional brake, during braking, the brake lever serves to drive and push the operation piston, adjustment piston, thread rod, connecting section and lining assembly in the inner caliper, whereby the lining assembly of the inner caliper together with the lining assembly of the outer caliper can clamp the brake disc to achieve a braking effect. However, the above components will not automatically restore. Therefore, after a long period of use, the lining assembly will be worn and have a thinner thickness. Under such circumstance, the gaps on two sides will be different from each other and an optimal braking effect will be hardly achieved. This will lead to safety problems.